This year will see the start of some real competition for Apple in the tablet space but not really threaten them. The thing you have to keep in mind is yes, Android sales grew a lot in the last year and that's important to driving app development because there are lots of users out there, but they didn't compete on even footing because the Android devices that sold did so for half the price. Apple is fighting back with the iPad mini, which is a fairly smart move to protect their market space and make it tougher for Google (as well as Microsoft to an extent) but this coming year will be the first time Apple will face real competition at the higher end.
Think of it as the parallel of the year the Samsung Galaxy S2 was released and this past year as the year the Galaxy S1 was released. The year the Galaxy S1 was released was the first time Apple was really challenged in the smartphone space with the EVO 4G, Droid Incredible, Droid X, and Galaxy S1 but Apple was still ahead. The next year the Galaxy S2 came out and for a time had some noteworthy advantages over the iPhone, even by the end of the year it had some strong differentiators but still wasn't definitively better. Finally, the Galaxy S3 came out and was definitively better and has remained so.
In the tablet equivalent we're just entering the Galaxy S2 year, we've got a year of Apple facing some real competition that isn't definitively better but has some definitive advantages over the iPad, for the first time there's a real reason to consider the competition aside from just price. This won't beat Apple, it will create some solid awareness for the competitors, which is a great start, both the Android and Windows tablets will get some limelight (Microsoft on the higher end, Android on the lower end to squeeze Apple respectively), but it won't be till the next year that we'll really see Apple pushed to the point where the iPad has a definitive rival, in other words we'll look back Fall of 2014 and see Apple really having been squeezed and beaten out by a few devices, which is when the tides will really turn as suddenly Apple is forced to play catch-up, which they won't have had to do in the tablet space until then.
For Windows Phone the road is slower and more bleak, Microsoft won't see major success until Windows Phone 10, this version will do better than the last, the Lumia 920 will probably triple the sales of the Lumia 900 but compared to overall market sales that's still a low number. Windows Phone 9 will finally put Microsoft on par overall with the competition and ahead in a few areas while behind in a few areas. That will finally drive adoption and awareness leveraged by the high end tablet success they'll have (on the high end Microsoft's value proposition beats everyone else, so does their price point but for people who want serious tablets Microsoft is the only way to go and that will threaten Apple's $800 range models) and adoption of Windows 8. If they are smart they'll have leveraged the Xbox 720 or whatever it's called as well. That'll be the first real market break for Microsoft a bit like when the mass market started to discover Samsung on the Galaxy S2, then the real success will come with Windows Phone 10 when they've got that initial momentum, critical mass, and finally a problem with distinctive advantages over Apple (so long as they can say the same about Android).